Screw driver for a multiaxial bone screw

Abstract

A screwdriver for driving a multi-axial its distal end for engaging the head of the bone screw for joint rotational movement. The screw driver includes an outer retention sleeve within which the inner shaft rotates freely. The outer retention sleeve releasably attaches to the yoke of the bone screw. In another configuration, the screwdriver comprises a screw engagement member affixed to the shaft for joint rotational movement therewith, the screw engagement member comprising a stop sized to seat within a slot of the bone screw yoke, the stop being configured to rotate the yoke upon rotation shaft. A releasable retention member is provided on the screw engagement member for releasably attaching the screwdriver to the bone screw.

1. A screw driver for driving a multi-axial bone screw into a vertebra of a spine, the bone screw including an elongate shaft having a threaded screw portion at the distal end and a screw head at the proximal end, and a yoke articulatingly attached to the screw head, the yoke having a slot therethrough for receiving a connecting rod and including a lower surface, the yoke having an opening communicating with the screw head, said screw driver comprising:
 an elongate inner shaft having a distal end and a proximal end, said inner shaft defining a driving tip at said distal end configured to engage the screw head for rotation thereof; 
 an outer retention sleeve disposed about said inner shaft and having a distal end and a proximal end, the inner shaft being freely rotatable within said outer retention sleeve and including said tip at the distal end thereof, the distal end of said outer retention sleeve configured to releasably engage the yoke for joint rotational movement therewith; and 
 a stop rotatably mounted on said inner shaft between the distal end of the outer retention sleeve and the driving tip at the distal end of said inner shaft, said stop being sized to seat within the slot of said yoke and configured to rotate with rotation of said yoke; 
 wherein rotation of said inner shaft rotates the elongate shaft of said bone screw relative to the said outer retention sleeve, said stop and said yoke which are joined in common. 
 
     
     
       2. A screw driver for driving a multi-axial bone screw into a vertebra of a spine, the bone screw including an elongate shaft having a threaded screw portion at the distal end and a screw head at the proximal end, and a yoke articulatingly attached to the screw head, the yoke having a slot therethrough for receiving a connecting rod and including a lower surface, the yoke having an opening communicating with the screw head, said screw driver comprising:
 an elongate shaft having a distal end and a proximal end, said shaft defining a driving tip at said distal end configured to engage the screw head for rotation thereof; and 
 a screw engagement member affixed to said shaft for joint rotational movement therewith, said screw engagement member comprising a stop sized to seat within the slot of said yoke and configured to rotate said yoke upon rotation of said shaft, and a flexible retention member for releasable attachment to said yoke. 
 
     
     
       3. The screwdriver of  claim 2 , in which the slot of said yoke is defined by a pair of upstanding opposed arms having interior surfaces and exterior surfaces respectively and wherein said flexible retention member comprises a pair of flexible elements releasably attachable to said respective pair of arms. 
     
     
       4. The screwdriver of  claim 3 , wherein each of said opposed arms of said yoke comprises an undercut extending respectively into an interior surface thereof and wherein each of said flexible elements is configured to provide an outward bias and having a projection for flexibly and releasably extending into said respective interior undercuts in said arms. 
     
     
       5. The screwdriver of  claim 3 , wherein each of said opposed arms of said yoke comprises a slot extending respectively into an exterior surface thereof and wherein each of said flexible elements is configured to provide an inward bias and having a projection for flexibly and releasably extending into said respective exterior slots in said arms. 
     
     
       6. The screwdriver of  claim 2 , further including a handle fixed to said shaft at said distal end thereof, said shaft being of length such that said distal end with said handle extends outside a patient as said bone screw is driven into a vertebra of the spine. 
     
     
       7. The screwdriver of  claim 2 , further comprising a guide wire lumen extending through said shaft to allow introduction of the shaft over a previously positioned guide wire.